Revolving unit heaters



Dec. 3, 1957 H. F. BRINEN 2,815,432

' REvoLvING UNIT HEATERS Filed Nov. 25, 195e 2 sheets-sheet 1 v /NVE/VmR.- wmm ATroRA/Ek Dec# 3, .1957. H. F. BRINEN 2,815,432

REvoLvING UNIT HEATERS' V 2 snQets-sleet 2 mea NovQzs. 195e V24" 'In' 1 1 L ',/M/ E/vro:

1 24 l By A7 70RNEK United States Patent Gflce 2,815,432 Patented Dec. 3, 1957 REVOLVING UNIT HEATERS Howard F. Brinen, Racine, Wis., assignor to Young Ruadiator Company, Racine, Wis., a corporation of Wiscousin Application November 23, 1956, Serial No. 623,879

4 Claims. (Cl. 219-39) This invention relates to what is known in the heatexchanger industry as revolving unit heaters.

A unit heater of the vertical type involves an overhead horizontally-disposed heating coil with a fan rotating in a horizontal plane to either blow or draw air through the and around the coil and direct a stream of heated air downwardly toward the floor. In order to effect a better distribution of this downwardly-projected air flow over a large area, a diuser, in the form of an annulus with two or more angulated air discharge outlets, is rotatively suspended from the under side of the heating coil. Such ya unit has come to be known in the heat-exchanger industry as a revolving unit heater. The revolving of this diffuser generally has been effected by a small, auxiliary motor operating independently of the fan motor.

Since the extensive development of the aircraft industry, a heating unit of this kind has become imperative equipment for conditioning hangars in the temperate or colder zones, where aircraft are in the course of assembly and/or servicing and repair.

In these zones, where aircraft have to be brought into hangars from outside temperaures below freezing, it is absolutely essential that the heated air from heating units be uniform and evenly distributed in order to insure an even and uniform increase of the temperature condition of such aircraft. Failure to insure such a uniform and even temperature change often results in serious distortion or rupture of portions of the aircraft.

It is a well-known fact that the column of air emanating from a revolving propeller type fan rotates quite violently in the same direction as the fan. When such an air column passes through a unit heaterwithout diffusers of any kindthe air column tends to take the form of a diverging cork screw. This is true especially of the draw-through type of unit heater.

If such a vertical-type unit heater has suspended therefrom a freely revolving diffuser, the cork-screw flow of air emanating from the fan so impinges on the diffuser and passes through to the discharge outlets as to convert the diffuser into a reaction device rotating on its axis at excessively high speeds; altogether too high for practical purposes of utilization of the air currents and the preservation of the equipment.

Such excessive rotation of a dituser on a vertical unit heater has not been permitted because the rotation of the diiuser has been restrained to a low speed by a small, motor-driven belt and pulley, gear and rack, or friction roller and track. In other words, this special motor-drive serves as a governor or brake on the tendency of the diffuser, if it were free, to respond to the iniluence of the air-flow emanating from the fan.

The main objects of this invention, therefore, are to provide an improved form of revolving unit heater wherein the speed of rotation is predetermined by the interpositioning of an air-How straightener between the fan and the diffuser; to provide an improved arrangement of air-flow straightener in the air-flow discharge of a unitheater mounting a rotatable diffuser; and to provide an improved air-flow straightening vane yarrangement of this kind which is so simple in form as to make its manufacture very economical and its functioning sure and efficient.

In the adaptation shown in the accompanying drawlugs;

Fig. l is a vertical sectional view of a revolving unit heater, of the draw-through type, constructed in accordance with this invention;

Fig. 2 is a transverse plan of the air-flow straightener taken on the plane of the line 2-2 of Fig. l;

Fig. 3 is an enlarged, fragmentary, sectional detail showing the diffuser bearing on the fan shroud mounting taken on the plane of the line 3 3 of Fig. 2; and

Fig. 4 is a fragmentary plan View of the upper end of the bearing support shown in Fig. 3.

The essential concept of this invention involves spanning the discharge outlet, of a propeller-type-fan revolving unit-heater, with a predetermined number of axiallydisposed, radially-extending airow straightening blades.

A draw-through type of revolving unit-heater embodying the foregoing concept comprises a heating coil 5 arranged within a housing 6 and mounting a motor-driven fan 7 rotating within a shroud 8 to which is secured an air-ow straightener 9 whereon is rotatively suspended a diuser 10.

The heating core 5 here is shown of annular form comprising concentric series of formed plate fin coils or coils made up of tubes and air side tins with inlet an-d outlet connections 11 and 12 for attachment to a suitable source of heated fluid (not shown) in a conventional manner.

The housing 6 comprises upper and lower members 13 and 14 bolted to opposite sides of the heating coil 5. The upper member has a centrally-located inverted frustoconical depending extension 15 whereon is mounted a fan motor 16 in the manner more fully shown and described in copen-ding application Ser. No. 437,254 filed June 16, 1954. Suitable means, such as eye bolts 17, are provided on this top housing member 13 for suspending the unit from suitable overhead structure. The lower housing member 14 has a centrally-located, depending annular rim 8 forming a heated-air discharge outlet for the housing which rim here constitutes a shroud for the fan 7 suspended on `a motor-shaft 19 for rotation in the upper portion of the shroud rim 8.

The air-straightener 9 comprises an annulus 20 supported at the ends of a plurality of vanes 21 bonded to a hub 22. The annulus 20 telescopes with the shroud 8 to which it is removably secured by a series of conventional fasteners. The vanes 21 are in the form of flat metal plates having the inner ends bonded to the hub 22 (see Fig. 4) and the outer ends flanged and bonded to the inner face of the annulus 20 (see Fig. 2). The functioning and number of Vthese vanes 21 will be explained in detail presently.

The diffuser 10 comprises a ring 23, bonded to a spider 24 rotatively suspended from the hub 22 of the air-ow straightener 9, and mounts a pair of oppositely angulated air-discharge outlets Axially, the spider 24 mounts a stud shaft 26 which is journaled in the hub 22 by suitable ball-bearing races 27 (see Fig. 3).

As hereinbefore noted, the helical air flow, caused by a propeller-type fan 7, discharged through a free rotating diffuser 10 would cause the diffuser to rotate by reason of the well-known Hero-engine principle. Such a rotation might be as high as 50 R. P. M. This would be entirely too rapid for a practical utilization of the air currents emerging from the diluser outlets 25. It is necessary, therefore, to effect a slow-down of the normal rotation 31 of the diffuser to a more practical optimum of between 2 and 7 R. P. M.

Such a brake on the normal rotative tendency of a freelymounted diffuser llt) can be effected by the use of the hereinshown air-how straightener 9 involving a predetermined number of axially-disposed vanes 2l. The fewer the number of vanes the faster the rotation of the diffuser; the greater the number of vanes the slower the rotation of the diffuser. Experiments have shown, for example, that 18 vanes will produce a rotative speed of the diffuser at between 11/2 to 2 R. P. M.

Although the air-flow vanes 21 might be a bit more effective if they were air-foil sections, it is believed that the expense of production of such a form would not adequately compensate for the use of fiat strips.

An important factor in determining the number of airfiow straightening vanes 2l is the torque required to insure the desired rotational speed of a particularly-constructed diffuser l0. It also is possible that, under certain circumstances, consideration may have to be given to the changing density of the air being handled by the fan.

Although, in the embodiment herein shown, the vanes are straight and disposed normal to the plane of the supporting annulus 2t), there may be situations where a slight inclination of the vanes will be found to effect a more uniform speed of rotation of the diffuser l0 for all the inuencing conditions.

Variations and modifications in the details of structure and arrangement of the parts may be resorted to within the spirit and coverage of the appended claims.

l claim:

l. A revolving unit heater comprising, a heating coil, a supporting housing for the coil having an air-discharge formed thereon below the coil, a motor-driven propellertype fan journaled on the housing below the heating coil to direct air through the air-discharge, a diffuser rotatively suspended on the housing, and a plurality of axiallydisposed air-fiow straightening vanes fixed in the housing directly below the fan and inwardly adjacent the diffuser to effect the rotation of the diffuser on the housing.

2. A revolving unit heater comprising, a heating coil, a supporting housing for the coil having an air discharge formed thereon below the coil, a motor-driven propellertype fan journaled on the housing below the heating coil to direct air through the air discharge, a diffuser rotatively suspended on the housing, and a plurality of axially-disposed air-flow straightening vanes fixed in the housing intermediate the fan and the diffuser to effect the rotation of the diffuser, the number of vanes being determined by the relationship of the effective pressure of the helical air-dov.' emanating from the fan and the desired rotational speed of the diffuser.

3. A revolving unit heater comprising, a heating coil, a supporting housing for the coil having a shroud formed thereon below the coil, a motor-driven propeller-type fan jourualcd on the housing with the fan disposed in the upper portion of the shroud below the heating coil, a diffuser having air discharge outlets angulated to the axis of rotation of the diffuser, and a plurality of airfiow straightening vanes fixed in axially-disposed radialrelationship in the shroud below the fan to effect the rotation of the diffuser on the fan shroud.

4. A revolving unit heater comprising, a heating coil, a supporting housing for the coil having an air discharge formed below the coil, a propeller-type fan journaled in the air discharge, an annulus attached to the housing below the air discharge, a plurality of air-flow straightening vanes fixed in axially-disposed radial relationship on the annulus and supporting a central hub, and a diffuser having air-discharge outlets angulated to the axis of rotation of the diffuser rotatively supported on the hub for rotation about a vertical axis, the number of vanes in the annulus being determined by the relationship of the effective pressure of the helical air-flow emanating from the fan and the desired rotational speed `of the diffuser.

References Cited in the file of this patent UNITED STATES PATENTS 2,000,112 Wheller May 7, 1935 2,221,703 Falco Nov. l2, 1940 2,457,934 Spieth Ian. 4, 1949 

